Download Fish Assemblages - Oregon State University

S. Gregory R. Wildman
L. Ashkenas K. Wildman P. Haggerty
Fish Assemblages
Fish Assemblages – Willamette River Basin
Fish assemblages are an important component of aquatic ecosystems of
the Willamette River Basin. Fish assemblages are recognized as sensitive
indicators of habitat degradation, environmental contamination, and overall
ecosystem productivity. Recent listings of fish species in the Willamette
River Basin under the federal Endangered Species Act (Oregon chub, spring
Chinook salmon, steelhead trout) and consideration of several species for
listing (coho salmon, cutthroat trout, bull trout) have caused the state to
evaluate the status of fish species and begin development of recovery plans
under the Oregon Plan for Salmon and Watersheds in 1997. Most management programs, both current and historical, have focused on particular
species of interest. We assembled information on the distribution of all fish
species to provide a spatial context for understanding the fish assemblages of
the Willamette Basin.
Sources of Information
We assembled data on locations of fish species from museum records,
agency reports, research databases, and field collections. These records were
limited to surveys in which there was a high likelihood that the species are
accurately identified (e.g., voucher specimens, taxonomic quality controls,
collections in the Oregon State University Fish Museum). Known locations
were entered into a GIS database for the WRB stream network (1:100,000).
The records were reviewed to determine whether it was probable that the
species would be distributed between known points of occurrence. Maps of
the potential distributions of each species were constructed. Projected
distributions were combined to identify the potential number of species
present within a reach or subbasin of the Willamette River Basin. Note that
this is not a direct measure of the richness of fish species at any point in a
stream or river. This projection represents potential distributions and is likely
to underestimate the richness of fish species.
Assemblages of Fish
The Willamette River Basin contains 31 native fish species and 29
exotic or introduced species (Table 22). Almost half the total richness of 60
fish species in the Willamette River Basin is made up of introduced species.
Of the 31 native species, more than one-fifth (7 species) are listed by either
the federal or state government as threatened, endangered, or sensitive. This
proportion (22%) is lower than the proportion of fish species listed across the
state of Oregon, which is 45% of the native species and subspecies.56 Oregon
ranks fifth in the United States in terms of total numbers of listed fish species
and stocks. The higher proportion across the state reflects the large number
of species at risk in more arid regions of the state. The native fish fauna
(Table 22; adapted from Ian Waite, USGS) are more sensitive to the impacts
of pollution than introduced species. Of the native species in the Willamette
Basin, only 13% are considered tolerant of pollution. Introduced species in
the Willamette system are characterized by fish that are tolerant of pollution
and habitat degradation, with 69% classified as pollution tolerant, such as
carp, bullhead and bass.
Patterns of Richness
Management of fish assemblages within the Willamette River Basin
requires an understanding of the distribution of fish throughout the stream
and river networks and the factors that are responsible for those distributions.
The Upland regions of the Willamette Basin are characterized by fewer fish
species than the Lowlands (Figs. 57, 58). Headwater streams typically
contain less than 10 fish species, and rivers that are major tributaries to the
mainstem Willamette generally support 15-25 species. The mainstem
Willamette River supports the highest local fish richness, with more than 35
species found in selected reaches. This overall pattern of greater richness in
lowland rivers is exhibited by the native fish species, and the tendency of
introduced species to occupy warmer, low gradient streams and rivers
accentuates this pattern.
The importance of lowland streams and rivers for fish assemblages is
also reflected at the watershed or subbasin scale (Fig. 57). Subbasins of the
Willamette in the Lowland region exhibit greater number of species than
Upland subbasins. Landscape frameworks for managing fish communities in
the Willamette River Basin require incorporation of basin-level patterns in
species richness and abundance of particular species. The lowland systems
present many challenges because of the high proportion of private land
ownership and the wide array of land use practices.
Fish assemblages in the Willamette River network are influenced by
both local habitats and larger landscape patterns and water management.
Major local factors are 1) availability of different types of habitats, 2)
availability of different types of food resources, and 3) interactions with
other species (e.g., predation, competitive interactions). Major landscape
factors that shape fish assemblages are 1) availability of groups of species
from major types of streams and rivers (e.g., large river systems, floodplains,
headwater streams, access to estuaries and ocean), 2) evolutionary and
geological history of the landscape, and 3) introduction of exotic taxa. These
larger scale factors increase the rate of longitudinal addition of species and
Number of Species
0 to 5
6 to 10
11 to 15
16 to 20
21 to 25
26 to 30
31 to 35
36 to 40
All Fish Species
Native Fish Species
Introduced Fish Species
Figure 57. Numbers of fish species known to occur within subbasins of the Willamette River Basin. Fish species presence is based on projected distributions between points of known species occurrence.
44
PNW Ecosystem Research Consortium
BIOTIC SYSTEMS
Number of Species
0 to 5
6 to 10
11 to 15
16 to 20
21 to 25
26 to 30
31 to 35
36 to 40
All Fish Species
Introduced Fish Species
Native Fish Species
Figure 58. Numbers of fish species within major stream reaches in the Willamette River Basin. Distributions are based on the same
database illustrated in Figure 57.
the maximum number of species observed. These influences are reflected in
the longitudinal pattern of cumulative numbers of potential fish species from
the headwaters of the Middle Fork of the Willamette River to the mouth in
Portland (Fig. 59). In this analysis, the cumulative number of species is
determined by increasing the cumulative number of species as each species is
encountered in a trajectory from small headwater streams to the mouth of the
Willamette River. The cumulative number of species increases steadily until
it reaches the mainstem Willamette River, at which point the number of
species is high and the rate of increase in species is not as rapid. Along the
mainstem, local numbers of fish species within 1 kilometer range from 8 to
24. Local numbers decrease in the Portland area because of habitat loss and
lower aquatic environmental quality. Introduced species increase markedly
when the river network enters the Lowland region.
Willamette River Fish Species
Number of Fish Species
50
40
Eugene
30
Albany
Newberg
Portland
Total
Native
Exotic
20
10
0
0
50
100
150
200
250
300
350
River Mile
Figure 59. Longitudinal pattern of cumulative number of fish species
(native, introduced, total) from the headwaters of the Middle Fork of
the Willamette River to the mouth in Portland. Fish species presence is
projected between points of known species occurrence.
Conclusions
• Lowland stream and river systems support greater numbers of fish
species than headwater streams and rivers.
•
Management of lowland systems, as well as the publicly owned
uplands, is critical for maintaining and restoring the fish fauna of the
Willamette River Basin.
•
Introduced species now make up almost half the fish assemblage of
the Willamette Basin and present potentially detrimental influences
on native fish communities.
Steelhead trout
Common carp
Table 22. Contemporary fish fauna of the Willamette River Basin.
Family
Common Name
Mainstem
Abundance
Mainstem
Location
Scientific Name
Origin *
Acipenseridae
Catostomidae
Catostomidae
Cottidae
Cottidae
Cottidae
Cottidae
Cottidae
Cottidae
Cottidae
Cyprinidae
Cyprinidae
Cyprinidae
Cyprinidae
Cyprinidae
Cyprinidae
Cyprinidae
Cyprinidae
Gasterosteidae
Osmeridae
Percopsidae
Petromyzontidae
Petromyzontidae
Petromyzontidae
Pleuronectidae
Salmonidae
Salmonidae
Salmonidae
Salmonidae
Salmonidae
Salmonidae
Salmonidae
Centrarchidae
Centrarchidae
Centrarchidae
Centrarchidae
Centrarchidae
Centrarchidae
Centrarchidae
Centrarchidae
Centrarchidae
Clupeidae
Cobitidae
Cyprinidae
Cyprinidae
Cyprindae
Cyprinidae
Cyprinidae
Cyprinidae
White sturgeon
Largescale sucker
Mountain sucker
Mottled sculpin
Paiute sculpin
Prickly sculpin
Reticulate sculpin
Riffle sculpin
Shorthead sculpin
Torrent sculpin
Chiselmouth
Leopard dace
Longnose dace
Northern pike minnow
Oregon chub
Peamouth
Redside shiner
Speckled dace
Threespine stickleback
Eulachon
Sand roller
Pacific lamprey
Western brook lamprey
River lamprey
Starry flounder
Bull trout
Chinook salmon
Coho salmon
Cutthroat trout
Mountain whitefish
Rainbow trout
Sockeye salmon
Black crappie
Bluegill
Green sunfish
Largemouth bass
Pumpkinseed
Redear sunfish
Smallmouth bass
Warmouth
White crappie
American shad
Oriental weatherfish
Common carp
Fathead minnow
Golden shiner
Goldfish
Tench
Grass carp
rare
common
common
absent
medium
common
common
rare
absent
common
common
medium
common
common
absent
common
common
common
common
rare
medium
common
medium
rare
rare
absent
common
rare
common
common
common
rare
common
common
absent
common
common
absent
common
medium
common
medium
absent
common
absent
rare
rare
rare
rare
low
all
all
tribs
all
all
all
tribs
tribs
all
all
all
all
all
tribs
all
all
all
all
low
all
all
all
all
low
tribs
all
low
all
all
all
low
all
all
lakes
all
all
lakes
all
all
all
low
tribs
all
lakes
low
low
low
low
Acipenser transmontanus
Catostomus macrocheilus
Catostomus platyrhynchus
Cottus bairdi
Cottus beldingi
Cottus asper
Cottus perplexus
Cottus gulosus
Cottus confusus
Cottus rhotheus
Acrocheilus alutaceus
Rhinichthys falcatus
Rhinichthys cataractae
Ptychocheilus oregonensis
Oregonichthys crameri
Mylocheilus caurinus
Richardsonius balteatus
Rhinichthys osculus
Gasterosteus aculeatus
Thaleichthys pacificus
Percopsis transmontana
Lampetra tridentata
Lampetra richardsoni
Lampetra ayresi
Platichthys stellatus
Salvelinus confluentus
Oncorhynchus tshawytscha
Oncorhynchus kisutch
Oncorhynchus clarki
Prosopium williamsoni
Oncorhynchus mykiss
Oncorhynchus nerka
Pomoxis nigromaculatus
Lepomis macrochirus
Lepomis cyanellus
Micropterus salmoides
Lepomis gibbosus
Lepomis microlophus
Micropterus dolomieui
Lepomis gulosus
Pomoxis annularis
Alosa sapidissima
Misgurnus anguillicaudatus
Cyprinus carpio
Pimephales promelas
Notemigonus chrysoleucas
Carassius auratus
Tinca tinca
Ctenopharyngodon idella
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Cyprinodontidae
Ictaluridae
Ictaluridae
Ictaluridae
Ictaluridae
Ictaluridae
Percidae
Percidae
Poeciliidae
Salmonidae
Salmonidae
Salmonidae
Salmonidae
Banded killifish
Black bullhead
Brown bullhead
Channel catfish
White catfish
Yellow bullhead
Walleye
Yellow perch
Western mosquitofish
Brook trout
Brown trout
Kokanee
Lake trout
common
rare
common
rare
rare
common
rare
common
common
absent
absent
absent
absent
low
low
all
all
low
all
all
all
all
tribs
tribs
lakes
lakes
Fundulus diaphanus
Ameiurus melas
Ameiurus nebulosus
Ictalurus punctatus
Ameiurus catus
Ameiurus natalis
Stizostedion vitreum
Perca flavescens
Gambusia affinis
Salvelinus fontinalis
Salmo trutta
Oncorhynchus nerka
Salvelinus namaycush
I
I
I
I
I
I
I
I
I
I
I
I
I
Adult
Trophic Group
Omnivore
Omnivore
Herbivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Herbivore
Insectivore
Insectivore
Piscivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Omnivore
Omnivore
Omnivore
Piscivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Piscivore
Piscivore
Insectivore
Carnivore
Insectivore
Insectivore
Omnivore
Omnivore
Omnivore
Omnivore
Insectivore
Omnivore
Insectivore
Omnivore/
Herbivore
Insectivore
Omnivore
Omnivore
Omnivore
Omnivore
Omnivore
Piscivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
Insectivore
* N - Native
I - Introduced
Willamette River Basin Atlas
2nd Edition
45